Due to the increasing cost of wood and the attendant cost of detailing wood pieces for building construction, there is a demand for alternatives to solid wood construction products. A particularly detailed piece used in construction of homes and other buildings is a wood window frame, particularly the two panel sliding sashes (double hung) wherein the panels lock together when in the closed position. This type of window requires intricate wood detailing since the profiles of the sashes require grooves to interlock with the exterior (immovable) portion of the window frame, as well as grooves to accommodate single and double pane glass, as desired. The invention may also be used to manufacture other profiles, such as round top, tilt, casement, etc.
Typically, wood sashes are made by intricate cuts into solid pieces of wood, with the final assembly, such as cutting drainage ports, waterproofing and sealing, done by hand. The present invention obviates the need for much of this handwork, while also providing an energy-efficient, durable, and low maintenance product.
A particular advantage of the present invention is that frame profiles may be provided which are energy efficient by use of materials which are more insulative than wood without the need for metal (such as aluminum) sealing or weather-protection. The use of metal on a frame profile diminishes insulative properties. The energy-conservation considerations are particularly important in view of increasingly stringent energy rating compliance standards for windows based on NFRC (National Fenestration Rating Council) U-Values which are being imposed by building code jurisdictions. To meet or exceed these standards, it is desirable to provide a frame profile which is not solid wood, requires minimal hand-work, and which avoids use of metal or energy-inefficient butyl rubber sealers between the glass panes and frame profile.
The present invention provides frame profiles that are not made of solid wood and which can be formed by a triple co-extrusion process whereby the core material of the frame profile is an extrudable foam plastic, at least partially coated with a weather-resistant plastic co-extrusion coating, and further co-extruded with a fluid material to form flexible flanges or ridges to provide sealing and water deflection where desired. The present invention also provides a triple co-extrusion die for making such extruded profiles.
It is therefore an object of the present invention to provide an improved method for making an extruded window sash comprising a foam plastic core material, an outer weather-resistant coating and flexible flanges for sealing and/or water deflection on the coating or core material.
It is a further object of the present invention to provide improved, elongated frame members made of synthetic materials which have improved energy-ratings and which are formed by a triple extrusion process.
It is yet another object of the present invention to provide extrusion dies for triple extrusion of a foam core material, a coating material and flexible flange forming material.
These and other objects will be apparent from the following description and claims, and from practice of the invention.